Tenant fit-out electrical work: the mistakes that push back opening day

In short

Tenant fit-out electrical jobs miss opening day because of late landlord approvals, unconfirmed supply capacity, and verbal variations - not slow wiring. Contractors who track each approval and variation against the programme are the ones who hand over on time.

The mistakes that push opening day back on tenant fit-out electrical jobs are rarely about the wiring. Late landlord approvals that were never tracked against the programme, a supply capacity assumption that turned into a DNO upgrade, and a set of verbal site changes that nobody confirmed in writing - these are the sequencing and sign-off failures that put handover at risk. The electrical work itself can proceed quickly once conditions are right. What the lighting and electrical contractor can control is making sure those conditions are confirmed before they become critical path items.

Landlord approval: the longest lead time nobody treats as a lead time

Most commercial fit-outs require written landlord consent before any Cat B works begin. In practice, that approval window runs anywhere from two to eight weeks, and it can extend considerably if the drawings submitted are incomplete or the landlord raises technical queries. Electrical contractors who join the project after layouts are finalised often find the landlord's consent has been submitted without full electrical drawings - or worse, that the approval stage has not yet started at all.

The specific failure pattern is this: the main programme shows "landlord approval" as a two-week phase sitting early in the timeline, but nobody has formally submitted, nobody owns the response tracking, and by the time the electrical contractor asks about it, the answer is still pending. First-fix cabling cannot start until approval is received. If approval comes back with comments - requiring changes to the electrical layout, load schedules, or fire alarm routing - those changes take further time to resolve. A two-week assumption has become five weeks, and the programme has absorbed none of that time.

Contractors who treat landlord approval as a tracked deliverable, with a submission date, a named contact, and a deadline on the programme, expose these delays before they are critical rather than after. The approval is not something the electrical contractor submits - but it is something the electrical contractor must confirm before committing a start date to anything downstream.

Supply capacity: the assumption that costs four weeks

The second common failure is assuming the existing electrical supply is sufficient without carrying out a capacity check. A tenant moving into commercial premises often takes the Cat A installation at face value. If the incoming service was sized for a previous occupier with lower demand - and the new tenant adds commercial kitchen equipment, server infrastructure, EV charging provision, or increased occupancy - the existing supply may not support the Cat B design.

Identifying a capacity shortfall early is a straightforward survey task. Identifying it after the Cat B electrical design is complete and the main contractor has started on other trades is a different problem. A supply upgrade requires a DNO application, and that process carries its own lead time. UK commercial electricity connection upgrades of meaningful scale can add three to twelve weeks to the programme depending on network reinforcement requirements at the local level.

The electrical contractor who carries out a capacity check at the design stage, before drawings are issued for landlord consent, is the one who surfaces this problem early enough for the programme to absorb it. The one who waits until materials are on order is the one managing a four-week slip and an unhappy tenant.

Verbal variations: how a word on site becomes a week's slip

The third category of delay is the one most directly in the electrical contractor's control, and the one most often treated as unavoidable. Site changes happen on every fit-out. The lighting layout moves because the ceiling grid changed. A partition wall is repositioned. The tenant adds a server room that was not in the original drawings. These changes are normal. The problem is not that they happen - it is that they are agreed verbally on site and not confirmed as formal variation orders.

A verbal instruction to move a circuit run or add a distribution board is not a variation order. Under standard UK construction contracts, verbal instructions from anyone other than the named contract representative need to be confirmed in writing. A contractor who proceeds on a verbal basis has done extra work, absorbed extra material cost, and extended the programme - without the formal paperwork that justifies a time or cost adjustment. When the opening date slips, there is no documented trail to explain why or to support a claim for extension of time.

The sequencing problem is that unconfirmed variations accumulate mid-programme. Each one individually seems minor. Collectively, they represent untracked changes to scope, unconfirmed cost exposure, and unmapped impacts on the programme. The electrical contractor who logs every site instruction as a works order or variation note, and tracks each to written confirmation, maintains a clear picture of what the actual programme looks like - not the original one from week one, but the real one at the point decisions need to be made.

Zigaflow's works orders functionality lets electrical contractors raise a works order against any instruction that arrives mid-job, attach it to the parent job record, and track it through to sign-off. That keeps the full scope of on-site changes visible in one place rather than scattered across site messages and verbal exchanges. Combined with project tracking, which shows milestone status in real time, a contracts manager can see at a glance which programme items are confirmed, which are pending approval, and which are at risk of sliding.

Tracking approvals against the programme

The unifying pattern across all three failure types - landlord approval, supply capacity, and verbal variations - is that they each involve a sign-off that needs to happen before something else can proceed, and none of them tends to be tracked systematically against the programme.

Landlord approval is needed before first-fix can start. DNO capacity confirmation is needed before the design is finalised. Written variation confirmation is needed before additional work is priced into the final account. When these sign-offs exist only in someone's email inbox or as a verbal assurance on site, they are invisible to the programme and to anyone managing delivery against it.

The approvals feature in Zigaflow lets electrical contractors attach a formal approval step to any item that requires sign-off before the next stage can proceed - whether that is a landlord consent milestone, a variation instruction, or a commissioning sign-off before handover. The approval is recorded, dated, and visible. If it has not been received by the date the programme requires it, that is visible too.

For electrical contractors working across multiple fit-out jobs simultaneously, this kind of real-time visibility is what separates a programme that stays on track from one that quietly slips. The tenant's opening day is set by the date the handover certificate can be issued. That date is set by the commissioning and certification sequence. That sequence is set by what was approved, confirmed, and tracked in the weeks before it. The wiring is rarely the problem. The sign-offs are.

Sources

• When Should You Appoint an Electrical Contractor for a Commercial Fit-Out?RSUK Group · accessed 2026-10-06
• Fit-Out Agreements: UK Tenant Legal ClausesSprintlaw UK · accessed 2026-10-06
• Commercial office fit out London: a practical guideUpKeep UK · accessed 2026-10-06
• Office Fit Out Mistakes That Increase Costs and Delay HandoverBarry Turner and Son · accessed 2026-10-06